I need help please someone if you can do it I would appreciate it a lot

What is the size of the matrix resulting from

Tom wants to order tickets online so that he and three of his friends can go to a water park the cost of the tickets is 16.00 per person there is also a 2.50 one-time service fee for ordering tickets online write an expression in term of n that represents the cost for n ordering tickets online

Ineed the solution to this problem and the steps.